Variation, Isolation Mechanisms, and Hybridization in Certain Toads.Albert P. BlairIsolation Mechanisms in Tree Frogs.Albert P. Blair

1942 ◽  
Vol 76 (762) ◽  
pp. 102-103
Keyword(s):  
Isolation Mechanisms

Isolation mechanisms in closely related grasshopper species Chorthippus albomarginatus and Ch. oschei (Orthoptera: Acrididae)

2007 ◽  
Vol 87 (3) ◽  
pp. 263-272 ◽  
Author(s):  
V. Yu. Vedenina ◽  
N. K. Kulygina ◽  
A. K. Panyutin
Keyword(s):  
Grasshopper Species ◽  
Isolation Mechanisms

Self-compatible sympatric Chamaecrista (Leguminosae-Caesalpinioideae) species present different interspecific isolation mechanisms depending on their phylogenetic proximity

2013 ◽  
Vol 299 (4) ◽  
pp. 699-711 ◽  
Author(s):  
Cristiana B. N. Costa ◽  
Jorge A. S. Costa ◽  
Luciano P. de Queiroz ◽  
Eduardo L. Borba
Keyword(s):  
Isolation Mechanisms

scholarly journals Toward the elucidation of reproductive isolation mechanisms in plants: diversity and universality

2019 ◽  
Vol 21 (1) ◽  
pp. 75-80
Author(s):  
Takahiro Tezuka ◽  
Katsuyuki Ichitani ◽  
Yuichi Matsumoto ◽  
Hai He ◽  
Tetsu Kinoshita ◽  
...  
Keyword(s):  
Reproductive Isolation ◽  
Reproductive Isolation Mechanisms ◽  
Isolation Mechanisms

scholarly journals Ecological Constraints Limit the Fitness of Fungal Hybrids in the Heterobasidion annosum Species Complex

2007 ◽  
Vol 73 (19) ◽  
pp. 6106-6111 ◽  
Author(s):  
Matteo Garbelotto ◽  
Paolo Gonthier ◽  
Giovanni Nicolotti
Keyword(s):  
Experimental Evidence ◽  
Species Complex ◽  
Fungal Species ◽  
Host Specialization ◽  
Heterobasidion Annosum ◽  
Postzygotic Isolation ◽  
Ecological Constraints ◽  
Closely Related Species ◽  
Parasitic Fungi ◽  
Isolation Mechanisms

ABSTRACT The ability of two closely related species to maintain species boundaries in spite of retained interfertility between them is a documented driving force of speciation. Experimental evidence to support possible interspecific postzygotic isolation mechanisms for organisms belonging to the kingdom Fungi is still missing. Here we report on the outcome of a series of controlled comparative inoculation experiments of parental wild genotypes and F1 hybrid genotypes between closely related and interfertile taxa within the Heterobasidion annosum fungal species complex. Results indicated that these fungal hybrids are not genetically unfit but can fare as well as parental genotypes when inoculated on substrates favorable to both parents. However, when placed in substrates favoring one of the parents, hybrids are less competitive than the parental genotypes specialized on that substrate. Furthermore, in some but not all fungus × plant combinations, a clear asymmetry in fitness was observed between hybrids carrying identical nuclear genomes but different cytoplasms. This work provides some of the first experimental evidence of ecologically driven postzygotic reinforcement of isolation between closely related fungal species characterized by marked host specificity. Host specialization is one of the most striking traits of a large number of symbiotic and parasitic fungi; thus, we suggest the ecological mechanism proven here to reinforce isolation among Heterobasidion spp. may be generally valid for host-specialized fungi. The validity of this generalization is supported by the low number of known fungal hybrids and by their distinctive feature of being found in substrates different from those colonized by parental species.

Reproductive biology and isolation mechanisms in rupicolous species of the Acianthera prolifera complex (Orchidaceae) occurring in southeastern Brazil

2011 ◽  
Vol 293 (1-4) ◽  
pp. 161-176 ◽  
Author(s):  
Marcos Cabral de Melo ◽  
Pedro Paulo Goulart Taucce ◽  
Eduardo Leite Borba
Keyword(s):  
Reproductive Biology ◽  
Southeastern Brazil ◽  
Isolation Mechanisms

scholarly journals Modulation of Prdm9-controlled meiotic chromosome asynapsis overrides hybrid sterility in mice

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Sona Gregorova ◽  
Vaclav Gergelits ◽  
Irena Chvatalova ◽  
Tanmoy Bhattacharyya ◽  
Barbora Valiskova ◽  
...  
Keyword(s):  
Meiotic Chromosome ◽  
Hybrid Sterility ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Recombination Hotspots ◽  
Chromosome Synapsis ◽  
Reproductive Isolation Mechanisms ◽  
Meiotic Recombination Hotspots ◽  
Isolation Mechanisms

Hybrid sterility is one of the reproductive isolation mechanisms leading to speciation. Prdm9, the only known vertebrate hybrid-sterility gene, causes failure of meiotic chromosome synapsis and infertility in male hybrids that are the offspring of two mouse subspecies. Within species, Prdm9 determines the sites of programmed DNA double-strand breaks (DSBs) and meiotic recombination hotspots. To investigate the relation between Prdm9-controlled meiotic arrest and asynapsis, we inserted random stretches of consubspecific homology on several autosomal pairs in sterile hybrids, and analyzed their ability to form synaptonemal complexes and to rescue male fertility. Twenty-seven or more megabases of consubspecific (belonging to the same subspecies) homology fully restored synapsis in a given autosomal pair, and we predicted that two or more DSBs within symmetric hotspots per chromosome are necessary for successful meiosis. We hypothesize that impaired recombination between evolutionarily diverged chromosomes could function as one of the mechanisms of hybrid sterility occurring in various sexually reproducing species.

scholarly journals Self Diagnostics and Isolation Mechanisms for Mixed Criticality Systems

2019 ◽  
Vol 15 (4) ◽  
Author(s):  
Asmaa Tellabi ◽  
Christoph Ruland ◽  
Karl Waedt ◽  
Abdelbast Sabri
Keyword(s):  
Critical Systems ◽  
Security Measures ◽  
Gate Arrays ◽  
Test Application ◽  
Self Test ◽  
And Performance ◽  
And Control ◽  
Isolation Mechanisms ◽  
Mixed Criticality

Virtualization is a technology that is frequently employed in computers and servers to provide isolation for execution environments, and to support the execution of multiple Operating Systems (OS) on the same hardware platform. In the embedded systems´ world, virtualization has been a rising trend, essentially because it offers an isolation mechanism that provides hardware manufacturer´ independence and it avoids obsolescence issues. The isolation mechanism supports safety and security measures, and assists in the certification of safety-critical systems. Virtualization offers improved performances, better transparency, portability and interoperability by integrating hardware and software resources, and also networking services into one computing entity. It makes the integration process of Mixed Criticality Systems (MCS) easier. For industries, FieldProgrammable Gate Arrays (FPGAs) hardware solutions provide the needed level of flexibility and performance. In this paper, a Self-test application is integrated in the hardware and also in the software level. The importance of self-test applications for Instrumentation and Control (I&C) systems will be discussed in the context of virtualization. For this implementation a type 1 hypervisor called Xtratum is used. An analysis of inter-partition communication channels´ performance will be provided including the implications multicore approaches will have on communication. The novelty of this work is to study the isolation impact multicore approaches can have on inter-partitions communications in Xtratum. Another novel aspect is the implementation of a self-test application in the hypervisor and the board as well. 

scholarly journals Study on the Rolling-Type Microvibration Isolation Mechanisms Based on Completely Elastic Contact

2019 ◽  
Vol 2019 ◽  
pp. 1-6
Author(s):  
Gaofeng Guan ◽  
Dengfeng Xu ◽  
Yu Zhu ◽  
Qiang Yu ◽  
Qiang Li
Keyword(s):  
Natural Frequency ◽  
Large Error ◽  
Common Mechanism ◽  
Rolling Motion ◽  
Elastic Contact ◽  
Load Range ◽  
Proposed Model ◽  
Pure Rolling ◽  
Rigid Contact ◽  
Isolation Mechanisms

The previous models of rolling-type mechanisms were built based on rigid contact and pure rolling motion, but when applied to ground microvibration isolation, a large error in the natural frequency was sometimes observed in the experiments. A new model of a common mechanism based on completely elastic contact is developed, and the expression of the natural frequency is provided under a microvibration condition. The experiments and analysis show that the proposed model is more accurate than the previous model, and the natural frequency is independent of the payload. The analysis shows that the proposed model is only suitable in the range of completely elastic contact, and the load range is provided after comparing the experimental results with existing theory.

Bio-Inspired Vibration Isolation: Methodology and Design

2021 ◽  
Vol 73 (2) ◽  
Author(s):  
Ge Yan ◽  
Hong-Xiang Zou ◽  
Sen Wang ◽  
Lin-Chuan Zhao ◽  
Zhi-Yuan Wu ◽  
...  
Keyword(s):  
Vibration Isolation ◽  
Variable Stiffness ◽  
Practical Applications ◽  
Vibration Isolators ◽  
Ultralow Frequency ◽  
Vibration Isolation Performance ◽  
Isolation Performance ◽  
Control Accuracy ◽  
Isolation Mechanisms ◽  
Auxiliary Mass

Abstract Various bio-inspired vibration isolators have been emerged in recent decades and applied successfully in the protection of sensitive components, improvement of operating comfort, enhancement of control accuracy, etc. They are generally developed by exploiting favorable nonlinearities in biological structures. The main contribution of this work is to provide a comprehensive review of recent studies on the bio-inspired isolators. The methodology of bio-inspired vibration isolation is proposed from the perspective of mechanics based on the elemental theory and design principles. The key isolation mechanisms are classified into three categories according to different dominant forces: stiffness adjustment mechanism, auxiliary mass mechanism, and damping mechanism, respectively. Some representative designs, performance analyses, and practical applications of each type of bio-inspired isolators are also provided. In bio-inspired isolators with variable stiffness, the inherent structural performances can be adjusted to deal with variation in external load. The auxiliary mass mechanism utilizes nonlinear inertial effects to achieve ultralow frequency vibration isolation. Unique damping mechanism of bio-inspired structures is often studied to protect devices and equipment from impact loads. Bio-inspired vibration methods can also be applied in active/semi-active control systems with advantages of low energy consumption and high robustness. Finally, the review ends with conclusions, which highlight resolved and unresolved issues and provide a brief outlook on future perspectives. This review aims to give a comprehensive understanding of bio-inspired isolation mechanism. It also provides guidance on designing new bio-inspired isolators for improving their vibration isolation performance.

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